Die head

ABSTRACT

A die head for roll forming threads or other formations on a workpiece in which a plurality of dies are rotatably supported in die holders bodily received in recesses in the head for rotation therein to move the dies toward and away from the axis of the head.

United States Patent Youtz et al. [451 Aug. 8, 1972 [54] DIE HEAD2,252,130 8/1941 Lamprecht et a1. ..72/126 72 Inventors: Donald E. Y EdM. E- 2,349,863 5/1'944 Hallberg ..72/126 1 bmde, both xg i 2,909,08710/1959 Powell ..72/103 l 3,196,650 7/1965 Kruse ..72/126 [73] Ass1gnee:Teledyne, Inc., Los Angeles, Calif. 3,352,139 11/1967 Cummings ..72/l04[22] Filed: Sept. 10, 1970 [21] Appl. No.2 70,988 PrimaryExaminer-Charles W. Lanham Assistant Examiner-E. M. Combs 52 U.S. c1...10/96, 72/104, 72/123, A'w'nekstmuch Neale Nies Km 408/148, 408/153,408/173 r [51] Int. Cl ..B23g 1/00 B23g 5/10, B23g 5/12 58 Field ofSearch ..10/111, 152, 94, 96; 72/102, [57] ABSTRACT 72/103, 104, 105,107, 123, 126; 408/ 146, A die head for roll forming threads or otherforma- 147, 148, 153, 173 tions on a workpiece in which a plurality ofdies are rotatably supported in die holders bodily received in [56]References Cited recesses in the head for rotation therein to move thedies toward and away from the axis of the head. UNITED STATES PATENTS631,159 8/1899 Echols ..72/104 3 Claims, 4 Drawing Figures PATENTEBm 8am 31681; 802

SHEET 10E 2 20 INVENTORS 2 mizrg rla reoos wzaww ATTOR YSPATENTEDAUBHBIBYZ 3.681.802

SHEET 20F 2 INVENTORS DONALD E.YOUTZ EDWIN M. EIGENBRODE ATTORN DIE HEADBACKGROUND or THE INVENTION Die heads of the general type with which thepresent invention is concerned have long been in widespread use for theformation of threads, splines, knurls, or like formations on cylindricalworkpieces.

Such die heads carry a number of dies, usually three, which roll inpressure contact with the workpiece as the workpiece and head arerelatively rotated and relative ly moved along the axis of theworkpiece. At the conclusion of the rolling operation the dies arewithdrawn radially from the workpiece which is then withdrawn axiallyfrom the head. The dies are then returned to their rolling position andthe rolling operation is repeated on successive workpieces.

The mechanism for supporting the dies in the die head is of criticalimportance to the successful performance of the head. The dies must bereadily moveable into and out of the rolling position and yet must berigidly supported in rolling position despite the imposition ofrelatively high loads on the dies. In the past, these objectives havebeen achieved to a certain extent but only by the provision of mechanismwhich is costly to manufacture and to replace after wear.

SUMMARY OF THE INVENTION With the foregoing considerations in mind it isthe principal purpose and object of the present invention to provideimproved means for supporting dies in a die head for rolling threads orlike formations on cylindri' cal workpieces which materially reduces theoriginal cost of the die head, and permits continued operation of thedie head with substantially reduced maintenance costs.

It is a further object of the present invention to provide improvedmeans for supporting dies in a die head with extreme rigidity to assureaccuracy of the forming operation and yet which is readily adjustablefor initial sizing, and which may be readily moveable between die-closedand die-open positions.

In attaining these and other objects, the present invention provides aunique die head having a central space for the reception of theworkpiece and a plurality of cylindrical recesses arranged around andopening into the space. The recesses are closed at one end by a faceplate detachably secured to the die head. A die holder is bodilyreceived in each recess, the die holder having a peripheral cylindricalsurface and having parallel end faces received with a close clearancefit between one end face of the die head recess and the inner surface ofthe face plate. Thus, essentially the entire external surface of the dieholder is utilized to journal the holder for rotation about its axis andto retain the holder against endwise movement.

Each holder carries a rolling die which is mounted for rotation in theholder about an axis spaced from the axis of the holder. Accordingly,when the holders are angularly displaced about the head axis the dieswill be moved toward and away from the axis of the work receiving space,either for initial sizing adjustment or to effect the opening andclosing movements of the die head.

Since both the die head recesses and the die holders are of essentiallycylindrical configuration, they may be machined to the necessary closetolerances at minimum expense. Also because of the unusual large bearingarea provided, wear on the die head and die holders is reduced to aminimum assuring an extended service life.

In the caseof extremely small diameters'of work it becomes increasinglydifficult to incorporate sizes which are within a desired range of a diehead of this type. This is especially true when a means of self openingroll dies of a relatively small diameter must be taken intoconsideration. The diameter of these dies must be decreased as the sizeof work becomes smaller in order to prevent their clashing together inclosed position. Because of the unique construction of the roll holdersof the subject invention the problem is solved as the small roll diescan be readily adapted to the roll holders.

Conventional means for opening and closing the die head as well as forachieving initial set up adjustment may be readily adapted to operatethe die holders of the present invention.

Additional objects and advantages of the invention will become apparentas the description proceeds.

THE DRAWINGS FIG. 1 is a central section through the die head of thepresent invention;

FIG. 2 is a side elevation of the die head partially broken away;

FIG. 3 is a rear elevation of the die head; and

FIG. 4 is a fragmentary section taken along line 4-4 of FIG. '1.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now more particularly tothe drawings, the thread rolling head comprises a hollow body member 20having a hollow shank 22 adapted to be mounted in or on a machinespindle in accordance with conventional practice.

The head body has an intermediate section for rotatably supporting anadjusting ring 24 and a closing ring 26 and an enlarged forward portion27 mounting the dies 28 and the associated holder assemblies 30 as willbe described.

The adjusting ring 24 is mounted for limited rotation on the head bodyand is held in adjusted rotated position by a pair of opposed adjustingscrews 32 (one shown) the inner ends of which engage a pin 34 carried bythe head body 20. The adjusting ring is held snugly against a shoulder36 on the head body by a snap ring 38.

A trip pin 40, forwardly biased by a spring 42, extends through theadjusting ring and at its rearward end is provided with a pair of pins44 and 46 adapted to engage the opposite faces of a trip plate 48mounted for rocking movement between the full line and dotted linepositions of FIG. 2 on a pivot pin 50 carried by the adjusting ring.

The closing ring 26 is mounted for limited rotation on the head bodybetween the rear face 52 of the head bodyenlargement 27 and the frontface of the adjusting ring 24. The closing ring is normally held againstrotation by a pair of latch pins 54 which are axially slidable in theadjusting ring and are moved axially by a trip plate 48 which isprovided with key hole slots 56, the side edges of which engage suitablyformed side slots in .the pins 54.

Normally the pins 54 occupy the full line position of FIG. 2 with theirinner ends received in openings 57in the closing ring to lock theclosing ring against rotation. When the pins are withdrawn from theclosing ring by movement of the trip plate to the dotted line positionof FIG. 2, the closing ring is angularly displaced by opening springs 58(one shown) compressed between the ends of a recess 60 in the adjustingring, and rearwardly projecting pins 62 (one shown) in the closing ring.

The structure thus far described is per se essentially conventional.

The present invention is concerned with means for mounting the dies 28and the association of the die mounting means with the previouslydescribed mechanism.

The dies 28 are of generally cylindrical form and are provided withsuitable peripheral formations complementary to the surface formationsto be produced on the workpiece. The apparatus of the present inventionpreferably includes three such dies which are mounted in equally spacedrelation around the axis of the head. In apparatus of this type it isessential that the dies be located. and oriented with precision; thatthey be equally adjustable by a simple mechanism; that they be readilyand simultaneously moveable between closed and open positions; that theybe supported with extreme rigidity to assure accuracy of the workdespite the development of rather high operating forces, and that theparts be subject to minimum wear and be relatively inexpensive tomanufacture. The mechanism for supporting the dies, which will now bedescribed in detail, satisfies all these objectives.

Each die 28 is mounted for free rotation on a cylindrical shaft 64, theopposite ends of which are received in aligned bores 66 and 68 in thedie holder 30. The shaft 64 is held against rotation by a lock screw 70,the inner end of which bears against a flat 72 on the adjacent end ofthe shaft 64. The end faces of the die 28 are received with a closeclearance fit with the end faces of a semi-cylindrical slot 74 in thedie holder, which provides a large bearing surface to assure continuedproper axial positioning of the dies 28.

The major portion of the outer surface of the die holder 30 is formed asa cylinder, the cylindrical surface being received in the correspondingsegment of the cylindrical surface 76 of the recess formed in theenlarged portion 27 of the head 20. The die holders 30 are axiallypositioned with a close clearance fit against the inner radial face 80of the recess by a face plate 82 secured as by a plurality of screws 84to the head 20.

A control pin 86, an integral part of the holder 30, extends through acircumferentially elongated slot 88 in the head body into a radiallyelongated slot 90 in the closing ring 26. Accordingly, upon rotation ofthe closing ring, the pins 86 are displaced circumferentially thusrotating each of the holders 30 about its axis. Since the die shaft 64is displaced radially from the axis of the holder 30 the dies arecorrespondingly displaced radially of the die head between open andclosed positions. Initial adjustment of the position of the holder 30for set up and sizing is effected by adjustment of the adjusting screws32 which rotate the adjusting ring 24 with respect to the head bodycarrying with it the closing ring 26 and the pins 86.

In operation, assuming the die head is closed, i.e., in the position ofFIG. 1, the workpiece is placed in a rotating chuck and the die head isaxially advanced onto the workpiece and the appropriate formation isproduced on the end of the workpiece. When a workpiece has been formedto the desired length, a stop member not shown, in fixed relation withthe workpiece contacts the end of the trip pin 40. The trip plate ispivoted to the dotted line position of FIG. 2 withdrawing the pins 54from the closing ring 26, which is then rotated by the opening springs58 to move the dies 28 out of contact with the workpiece which is thenwithdrawn. The closing ring is then restored to its closed position bymanual or mechanical operation of a projection 92 formed integrally withthe closing ring. As soon as the openings in the closing ring arealigned with the pins 54 the spring 42 restores the trip plate 48 to itsoriginal position locking the closing ring in its original position.

It will be noted that the cylindrical body of the holder 30 isinterrupted by a flat surface 94 providing the clearance necessary topermit the apparatus to move between the closed and open positions andto permit the surface of the dies 28 to project into contact with theworkpiece. At the opposite edges of the flat surface 94 the surface ofthe holder 30 is notched to provide radial surfaces 96 and 98 whichfunction as scrapers acting against the cylindrical surface 76 of thehead body recess to eliminate chips from adjacent cutting operations ordirt which might otherwise be wedged between the outer surface of theholder 30 and the mating recess surface.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:

l. A die head comprising a body member having an annular die mountingportion and a central opening for the reception of a workpiece, saidbody portion having a plurality of recesses equally circumferentiallyspaced about the axis thereof, said recesses having cylindrical surfaceportions the axes of which are parallel with the axis of said bodymember and said recesses intersecting and opening into said centralopening, a die holder in each of said recesses, said die holders havingcylindrical peripheral surfaces in engagement with the cylindricalrecess surfaces to be rotatably supported thereby and each die holderhaving a recess intermediate its ends, each recess opening laterally ofsaid holder into said central opening, means on each die holder forsupporting a die in said die holder recess for rotation about an axisspaced from the axis of said holder, and means for simultaneouslyrotating each of said holders about their axes to move said dies towardand away from said axis of said head.

2. A die head according to claim 1 wherein said body member has a radialend face essentially perpendicular to the axis of said body member andwherein said recesses in said body member extend to said radial 3. Thedie head according to claim 2 wherein the recesses in said die holdershave side faces essentially perpendicular to the axis of said bodymember for engagement with the opposite end faces of a die received insaid recess.

1. A die head comprising a body member having an annular die mountingportion and a central opening for the reception of a workpiece, saidbody portion having a plurality of recesses equally circumferentiallyspaced about the axis thereof, said recesses having cylindrical surfaceportions the axes of which are parallel with the axis of said bodymember and said recesses intersecting and opening into said centralopening, a die holder in each of said recesses, said die holders havingcylindrical peripheral surfaces in engagement with the cylindricalrecess surfaces to be rotatably supported thereby and each die holderhaving a recess intermediate its ends, each recess opening laterally ofsaid holder into said central opening, means on each die holder forsupporting a die in said die holder recess for rotation about an axisspaced from the axis of said holder, and means for simultaneouslyrotating each of said holders about their axes to move said dies towardand away from said axis of said head.
 2. A die head according to claim 1wherein said body member has a radial end face essentially perpendicularto the axis of said body member and wherein said recesses in said bodymember extend to said radial face, the recesses having an inner end faceessentially perpendicular to the axis to said body member and said dieholders having one end face in engagement with said inner end face ofsaid recess, and a face plate detachably secured to said radial endsurface of said head and having surface portions in engagement with theopposite end face of each of said holders.
 3. The die head according toclaim 2 wherein the recesses in said die holders have side facesessentially perpendicular to the axis of said body member for engagementwith the opposite end faces of a die received in said recess.